The present invention relates generally to a method and apparatuses for the change of thermal flow between thermal heat sources and thermal heat sinks. The method involves the electrochemical formation and removal of tree-like crystals or dendrites within structures through which heat is passing.
There are many examples in the prior art of heat transfer switches which typically comprise elements which mechanically provide for changes in thermal conduction between the heat source and sink. Typically these devices control the heat flux through mechanical variations of a gap between the source and the sink. This gap typically contains a liquid or gas whose primary function is to provide a path for conductive heat transfer.
Very large changes in heat transfer are possible when metal-metal contact replaces a gap filled with an insulating medium. However, the prior art of heat transfer switches involves the use of very complicated mechanisms which do not lend themselves to fabrication into flexible foils or films. Thus their use has been largely limited to controlling the heat management in man-made space vehicles.
There are examples in the prior art of thin flexible surfaces designed to control transfer of heat perpendicular to the surface. These examples, however, achieve only very modest variations in heat transfer. In the U.S. Pat. No. 4,515,206, to Carr, active regulation of heat transfer is achieved by placing liquid crystal material between thin foils of metal. By applying a strong electric field between the enclosing foils, changes in the orientation of the liquid crystal result. These changes in orientation produce changes in the thermal conductivity between the foils. Unfortunately these effects tend to be very small even for large applied fields and require the continuous application of electrical power.